I have a Rinnai tankless on-demand water heater. The unit is making a high-pitched whistling noise.

I have:

-Unplugged the unit from the electrical wall socket.

-Turned the gas valve to the off position.

-Turned the cold water intake line valve to the off position.

-Turned the hot water outlet valve to the off position.

-I have removed the front panel and used compressed air to blow most of the dust off of the unit.

The unit has been in this state for an hour and It still whistles. Why?

  • Is this unit inside or outside? Where does the vent terminate? Commented Apr 22, 2021 at 2:49
  • The unit is on the inside wall. There is a 90 degree bend in the vent just above the unit. This vents to the outside of the house.
    – GBG
    Commented Apr 22, 2021 at 3:00

1 Answer 1


An exterior garden hose spigot was on, leaking, and whistling. Turning off the outside spigot stopped the whistling in the Rinnai. The water heater must have acted as an amplifier for the sound travelling through the pipes of the house.

  • Great job finding it! Be sure to give yourself a check mark.
    – FreeMan
    Commented Apr 22, 2021 at 12:57

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